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Title: Sol-gel processing and phase characterization of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders

Abstract

Monolithic Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders were prepared by sol-gel processing. The process involved the precipitation of Al(NO{sub 3}){sub 3}.9H{sub 2}O with NH{sub 4}OH in excess water to form boehmite (AlOOH). XRD indicates that the subsequent thermal reaction proceeds by the phase transformation sequence AlOOH, {gamma}-, {delta}-, {theta}-, to {alpha}-Al{sub 2}O{sub 3}. The {sup 27}Al NMR spectra indicate a gradual increase in the proportion of Al in the tetrahedral sites of the {gamma}-, {delta}- and {theta}-Al{sub 2}O{sub 3} formed at increasing calcination temperatures. Complete transformation to octahedral Al ({alpha}-Al{sub 2}O{sub 3}) is marked by the abrupt disappearance of tetrahedral Al. Al{sub 2}O{sub 3}/SiC nanocomposite powders were prepared by adding {alpha}-SiC powder to the boehmite precursor at the precipitation stage. Upon heating, the {sup 29}Si NMR spectra of the Al{sub 2}O{sub 3}/SiC powders reveal {alpha}-SiC, Al{sub 2}O{sub 3}.xSiO{sub 2} and SiO{sub 2} phases. Stable {alpha}-Al{sub 2}O{sub 3} and {alpha}-Al{sub 2}O{sub 3}/SiC nanocomposite powders are formed at 1200 and 1300 deg. C, respectively. It appears likely that the presence of SiC modifies the thermal behaviour of the Al{sub 2}O{sub 3} in the nanocomposites by stabilising the Al{sub 2}O{sub 3} phases with concomitant oxidation of SiO{sub 2}.

Authors:
 [1];  [2]
  1. Department of Physics, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand). E-mail: sukanda@chiangmai.ac.th
  2. School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington (New Zealand)
Publication Date:
OSTI Identifier:
20891662
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 41; Journal Issue: 4; Other Information: DOI: 10.1016/j.materresbull.2005.10.014; PII: S0025-5408(05)00388-0; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM OXIDES; AMMONIUM HYDROXIDES; CALCINATION; CALORIMETRY; CERAMICS; COMPOSITE MATERIALS; HEATING; NANOSTRUCTURES; NITRATES; NITROGEN OXIDES; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; POWDERS; SILICA; SILICON OXIDES; SOL-GEL PROCESS; X-RAY DIFFRACTION

Citation Formats

Jiansirisomboon, Sukanda, and MacKenzie, Kenneth J.D. Sol-gel processing and phase characterization of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders. United States: N. p., 2006. Web. doi:10.1016/j.materresbull.2005.10.014.
Jiansirisomboon, Sukanda, & MacKenzie, Kenneth J.D. Sol-gel processing and phase characterization of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders. United States. doi:10.1016/j.materresbull.2005.10.014.
Jiansirisomboon, Sukanda, and MacKenzie, Kenneth J.D. Thu . "Sol-gel processing and phase characterization of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders". United States. doi:10.1016/j.materresbull.2005.10.014.
@article{osti_20891662,
title = {Sol-gel processing and phase characterization of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders},
author = {Jiansirisomboon, Sukanda and MacKenzie, Kenneth J.D.},
abstractNote = {Monolithic Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/SiC nanocomposite powders were prepared by sol-gel processing. The process involved the precipitation of Al(NO{sub 3}){sub 3}.9H{sub 2}O with NH{sub 4}OH in excess water to form boehmite (AlOOH). XRD indicates that the subsequent thermal reaction proceeds by the phase transformation sequence AlOOH, {gamma}-, {delta}-, {theta}-, to {alpha}-Al{sub 2}O{sub 3}. The {sup 27}Al NMR spectra indicate a gradual increase in the proportion of Al in the tetrahedral sites of the {gamma}-, {delta}- and {theta}-Al{sub 2}O{sub 3} formed at increasing calcination temperatures. Complete transformation to octahedral Al ({alpha}-Al{sub 2}O{sub 3}) is marked by the abrupt disappearance of tetrahedral Al. Al{sub 2}O{sub 3}/SiC nanocomposite powders were prepared by adding {alpha}-SiC powder to the boehmite precursor at the precipitation stage. Upon heating, the {sup 29}Si NMR spectra of the Al{sub 2}O{sub 3}/SiC powders reveal {alpha}-SiC, Al{sub 2}O{sub 3}.xSiO{sub 2} and SiO{sub 2} phases. Stable {alpha}-Al{sub 2}O{sub 3} and {alpha}-Al{sub 2}O{sub 3}/SiC nanocomposite powders are formed at 1200 and 1300 deg. C, respectively. It appears likely that the presence of SiC modifies the thermal behaviour of the Al{sub 2}O{sub 3} in the nanocomposites by stabilising the Al{sub 2}O{sub 3} phases with concomitant oxidation of SiO{sub 2}.},
doi = {10.1016/j.materresbull.2005.10.014},
journal = {Materials Research Bulletin},
number = 4,
volume = 41,
place = {United States},
year = {Thu Apr 13 00:00:00 EDT 2006},
month = {Thu Apr 13 00:00:00 EDT 2006}
}